Table of Content

25 June 1999, Volume 19 Issue 2

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Cryopreservation of Expanded Mouse Blastocysts in Pellets by Vitrification

ZHU Shi-恩, ZENG Shen-Ming, ZHANG Zhong-Cheng

1999, 19(2):  67-71. 

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"The cryopreservation of expanded mouse blastocysts in pellets by vitrification was studied at 25℃ with EFS30 solution (contains 21 % ficoll，0.35mol/L sucrose and 30% ethylene glycol) as a cryoprotectant. The expanded blastocysts in group 1 were equilibrated in EFS30 solution for 1 min，then pluged into liquid nitrogen, while in group 2 they were pretreated with 10% ethylene glycol for 5 min and equilibrated in EFS 3 0 solution for 1 min，then pluged into liquid nitrogen. The development rate and the hatch rate of blasto-cysts in group 1 were 100% and 70% respectively after being thawed and cultured , while in group 2 they were 98% and 63% respectively. The development rates in group 1 and 2 didn’t differ significantly from that of control (P＞0.05 ). The percentages of pregnant dams and full - term pregnancy offsprings were 90% and 71% respectively in group 1， while in group 2 they were 81 % and 58% respectively .after the thawed expanded blastocysts were transplanted into pseudopregnant mice. There were no significant differences in the percentages of pregnant dams and full - term pregnancy offsprings between the cryop-reserved groups and the control (P＞0.05). "

A Dog Model of Essential Hypertension Induced by Vascular Compression of Ventrolateral Medulla Oblongata

GAO Yuan-Zheng, LUO Qi-Zhong, LI Shan-Quan, XIONG Wen-Hao, QIU Yong-Ming, YE Nai-Qing, PAN Yao-Hua, ZHOU Zheng-Wen, YIN Yu-Hua

1999, 19(2):  72-75. 

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"Twelve adult mongrel dogs of both sexes were randomly divided into two groups equally. In experimental group the greater omentum was extensively lengthened ancl brought through a subcutaneous tunnel up to the left ventrolateral medulla oblongata and the root entry zone (REZ) of the ninth and tenth cranial nerves,and this part of the medulla oblongata was compressed by blood vassel anastomosis formed between omentum ancl soft tissue overlying the medulla oblongata. While in control group，the omentum was transplanted to the surface of the cerebellum. The results showed that the increase in blood pressure was statistically significant in experimental group (P＜0.01).but not in control group (P＞0.05). The results suggested that essential hypertension may be associated with neurovascular compression of the left ventrolateral medulla oblongata. "

Establishment of a Model of Hypothermia Intervention after Hypoxic-Ischemic Brain Damage in Newborn Rats

QIN Mei-1, WANG Xing-He-1, FAN Shao-Zeng-1, YANG You-Ming-2

1999, 19(2):  76-81. 

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To establish the models of moderate hypothermia intervention after hypoxic - ischemic brain damage (HIBD) in newborn rats,the posthypoxic - ischemic 7day -old rats,weighing 14g±2g，were divided into 4 groups. The rats in group 1～3 (i. e. Hy24 group，n=26 ;Hy48 group14；Hy72 group，n=20) were placed in water bath stabilized at 29℃ for 24h,48h .and 72h respectively and fed with formular milk at the same time,and those in group 4 (RoT group,n=44) were stayed in a breeding room (25～29℃) with dams. After the insult ,the levels of blood glucose,blood gas andplasma lactate were monitored. Two weeks after HIBD,body weight increase percents (WIP) .right brain injury scores (BIS) and percents of necrotic neurons in right hippocampus (HNNP) were determined. The results showed that the levels of blood glucose in the animals fed with formular milk for 72 h were kept at normal levels (＞3 mmol/L) ,and the brain temperatures were decreased by 4～5℃ after hypothermia intervention. At 6h after HIBD there were hypoxemia and metabolic acidosis in RoT group,but in Hy24 group all rats recovered with nearly normal levels of blood gas and plasma lactate. Two weeks after HIBD.WIP was significantly lower in RoT group than in Hy24 group (88.0% vs 134.5%，P＜0.01),and not different between Hy48 and RoT groups (P＞0.05). The results of neuropathological observation of the brains indicated that BIS and HNNP in Hy groups were significantly reduced by 53%～89% with 24h to 72h hypothermia intervention specially in Hy72 group,as compared to RoT group. The authors provided successful model of hypothermia intervention after HIBD in newborn rat by formular milk feeding,and found that the optimal effects of moderate hypothermia intervention after HIBD were reached when the intervention lasted 72h and made the brain temperature decreased by 4～5℃。

Establishment of Acute Lung Injury Model by Injection of Endotoxin under Mechanical Ventilation in Rabbit

ZHAO Dan-Hong-1, WU Zhao-Han-1, SUN Bo-2

1999, 19(2):  82-86. 

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To establish acute lung injury model, New Zealand White rabbits were divided into model group (n=13) and control group (normal group, n=5). The animals in the model group were injected intravenously with Escherichia coli lipopolvsaccharide (LPS) 0.1mg/kg (pretreated with one tenth of the total dose 12h before). Gas change, lung mechanics, blood pressure and pulse were monitored under mechanical ventilation. The lung injury was observed 8h after the second injection of LPS. The measurement values for PaO₂/FiO₂ alveolar - arterial O₂ gradient (A -aD0₂) , intrapulmonary shunting (Qs/Qt)，Cdyn and Rrs showed that the pulmonary function in the model group was significantly worse than that before the second injection of LPS and that in the control group (P＜0.01). In the model group, PaO₂/FiO₂ was below 40kPa, atelectasis, edema, hemorrage ancl inflammatory infiltrates were also seen in the lung sections 14h after the 2nd injection of LPS，white blood cell count and total protein (TP) content were significantly increased in BALF，ancl wet/dry weight ratio of the lung was also significantly increased. It is concluded that acute lung injury model has been established within 8～14h by injection of endotoxin intravenously based on impaired gas change, lung mechanics, ancl increased blood cell count and TP content in BALF.

Effects of Temperatures and Light - Dark Cycles on Propagation of Meriones Meridianus and Cricetulus Migratorius

LIAO Li-Fu, LI Wei

1999, 19(2):  87-89. 

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The descent of testicles and reproduction of Meriones meridianus jei and Cricetulus migratorius in breeding rooms were observed in four conditions ：under the artificial illumination with a regime of D8 : L16 at temperature 15～20℃ or 10～14℃，and utilizing the sun-shine with a regime of Dll. 5～15 : L12. 5～9 at two temperatures mentioned above. The results showed that both M. meridianus and C. migratorius belong to the rodents of long sunshine type. With the lighting regime D8 : L16,raising temperature could lead the testes to descend,and the copulations were effective by more than 43d and 21d’s stimulating (15～20℃) in M. meridianus jei and C. migratorius respectively. With the lighting regime Dll. 5～15 : L12. 5～9，raising temperature could stimulate the testes to descend in C. migratorius that could also take part in reproduction by more than 60d’s stimulating (1.5～20℃) »but not in M. meridianus jei.

Study on Pregnancy of Recipients and Survival Rhte of Founder Mice in Preparation of Transgenic Mice

CHEN Jian-Quan, LUO Jin-Ping, ZHOU Ru-Jiang, CHENG Guo-Xiang

1999, 19(2):  90-92. 

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"The pregnancy of the recipients and survival rate of founder mice during the production of transgenic mice with twelve genes were studied. The results showed that 75 of 98 pregnant recipiens had parturition 19～21 days after embryo transference and the survival rate of their progenies was 93.5% (374/400). 16 of 98 pregnancy recipients had natural parturition 22～24 days after embryo transference, 7 of 98 pregnancy recipients had parturition by cesarean section 22～23 days after embryo transference, and the survival rates of their progenies were 0% (0/52) and 60.7% (17/28) respectively. The results indicated that the pregnancy of recipients was similar to that of normal ICR mouse. The survival rate of the progenies from cesarean section is higher than that of those from natural parturition in prolonged pregnancy recipients. "

Effects of Thymosin on Expression of HBV DNA in HBV Transgenic Mice

ZHANG Yi-Jun, LI Zhuo-Liang, WANG Bao-Kui, CHEN Wen-Yin, ZHANG Gu-Sheng

1999, 19(2):  93-95. 

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To observe the effects of thymosin on the expression of HBV DNA，HBV transgenic mice were divided into 3 groups. The animals in group 1 were intraperitonealy injected with native thymosin , while in the 2 control groups with pHGF and saline respectively，for 3 month at a same dose of 3 mg per mouse (injection volumes in 3 groups were 0.75ml) per day. The animal blood was sampled periodically for HBV DNA assay. It was found that the loss rate of HBV DNA in group 1 ranged from 22% (2/9) to 55% (5/9). Twenty two days after the termination of treatment with thymosin,the loss rate remained 22% (2/9),while in the 2 control groups it was 0%, The result suggested that native thymosin could inhibt the expression of HBV DNA in HBV transgenic mice.

A Focal Cerebral Ischemia Model by Occluding Middle Cerebral Artery in Rat

ZHANG Yu-Xun-1, LI Jian-Jun-1, WANG Yuan-Zhan-2, YANG Pei-Liang-2

1999, 19(2):  96-96. 

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The single lateral middle cerebral arteries (MCA) of SD rats were occluded with electric heating coagulation following the ligation of ipsilaternl common carotid artery (CCA). After 7 clays,the focal cerebral ischemia in the animals were evaluated with a neurologic examination grading system,histochemistry staining techniques and a computer image analytic system. The results showed that focal cerebral ischemia model was duplicated . ancl was reliable and practical for the studies on brain infarction and its therapy.

Progress of Inbreeding of Hairless KM Mice

ZHOU Shu-Pei, TIAN Feng, KANG Ai-Jun, WANG Zhao-Chuo

1999, 19(2):  117-118. 

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The hairless mutant mouse was found in KM closed colony. The “hairless” gene was retained by backcrossing and brother X sister mating system. The inbreeding had progressed to the 18th generation since February 1995. The average generation interval was 71.5 days (55-116 days). The result of coat color test crossing of the F18 with DBA/2 showed that the color genes in F18 were homogenous. The hairless mice start to shed at the age of 4 weeks and lose almost all hairs at the age of 5 weeks. The sparse and short hairs gradually appear after the age of 6 weeks. Clean hairle'ss mice have been derived through caesarean section.